As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Information handling systems employ central processing units (CPUs) to perform processing tasks for the system. Some CPUs are configured to operate in a “Turbo Boost” mode during which the CPU is enabled to run at a higher clock rate than its base operating frequency (referred to as dynamic CPU overclocking) during periods of high processing demand as requested by the operating system (OS) of the information handling system. CPU processor performance states are typically defined for a CPU by the Advanced Configuration and Power Interface (ACPI) specification, and the OS typically requests the highest CPU performance state for the maximum Turbo Boost mode, which is typically limited only by electrical (power, current) and thermal limits of the CPU. Thus, Turbo Boost mode may be allowed upon OS request as long as the CPU remains within its defined electrical and thermal limits, and/or based on other parameters. For example, the OS may request maximum processor frequency (ACPI P0) and the power management unit (PMU) of the CPU may allow or deny the request based upon number of active processor cores, estimated current, estimated power and processor temperature if and how much turbo will be applied.
Turbo boost implementation provides advantage for burst type operations which are typical of client type workloads. During turbo boost, the CPU is allowed to operate significantly higher than the (Thermal Design Power) TDP for short periods of time. When workloads are bursty in nature this results in the processor performance appearing to be that of a processor operating at a much higher frequency. The side effect is the need to design the power delivery system to support these very high peak power demands. When a system is operating on battery power these power peaks must be supplied by the battery, when operating on AC adapter these power peaks must be supplied by AC adapter during low battery conditions.
During system operation, implementation of maximum turbo boost mode can cause very high instantaneous peak supply current (ICC) inrush to the CPU that can temporarily overwhelm the power delivery system for an information handling system, such as the battery pack and/or AC adapter of a battery-powered information handling system such as a notebook computer or tablet computer. This is true even for relatively low power information handling systems. For example, maximum ICC generation for an information handling system with average power draw of 15 Watts can reach 50 Watts during initiation of Turbo Boost mode. Conventional ways of accommodating high power demand for a Turbo Boost mode include over designing the power delivery system including AC adapter and battery power capacity. However, such over-designed (higher capacity) AC adapters and batteries result in increased system weight, system cost, and heat generation during operation. Larger over-designed batteries take up additional space and increase system weight, such that they are often not practical for modern portable information handling system devices. Consequently, smaller batteries are typically used for such portable devices, which compounds the high ICC input power problem during Turbo Boost mode operation.
Large banks of capacitors have been coupled to a supply current node for a processor to help satisfy high processor inrush current in desktop information handing system applications. In such conventional applications, the capacitor banks are continuously coupled to the current supply node for the processor, and therefore require high continuous supply current to be delivered at all times to both the capacitor bank and the processor load. Such capacitor banks are typically too large to be practical for mobile battery-powered applications, and suffer relative high energy leakage due to capacitance equivalent series resistance (ESR), even at relatively low stand by voltage levels, due to large capacitance value required.